McGill University Thèses et mémoires publiés en 2009

La matière organique dissoute (DOM) est composée de particules dissoutes et colloïdales passant au travers un filtre de 0.45 Ilm. L'importance de DOM dans les sols est liée à son rôle dans la pédogenèse, les processus d'altération des minéraux, l'assimilation par les plantes et microbes, ainsi que l'acidification des plans d'eau et des sols.[...]  Lire la suite

Travis, Lisa de Mena (Internal/Supervisor)  Lire la suite

Application of eye movement measurement is especially significant in Neuroscience. Results from eye tracking can give valuable insight into the correlation between neural activity and eye movements. Abnormalities in the eye movements also provide information regarding diagnosis and progress of neurological diseases such as dementia. Another application is in developing human-computer interfaces as a means of communication for the severely handicapped. Although there are numerous eye tracking techniques available, the magnetic search coil method has been prominently used by researchers due to its high accuracy and precision. This technique typically requires the subjects head to be fixed for accurate measurements …  Lire la suite

There is a direct relationship between the development of colon cancer and exogenous factors, such as diet. The immunomodulatory effect of probiotic bacteria has been postulated earlier; however, due to low clinical efficacy and associated limitations they have not been devised as cancer theraphy and preventative procedures. One of the main obstacles is the efficient delivery of live bacterial cells to targeted sites. The work contained in this dissertation aims to develop and evaluate a yogurt based formulation containing microencapsulated live probiotic bacterial cells for use in colon cancer prevention and theraphy. Alginate – poly-L-lysine – alginate (APA) and alginate-chitosan …  Lire la suite

There is a growing recognition among many who work with society's most disadvantaged cultural groups that cultural identity might be a primary issue related to their psychological adjustment. From his experience with Aboriginal peoples in Canada and inner city African American communities in the United States, Taylor (1997, 2002) theorizes that without a clear cultural identity, a person has no normative template with which to construct a clear personal identity, and by extension, to achieve positive self-esteem and well-being. The program of research I describe in the present thesis represents the first attempt to empirically investigate the extent to which …  Lire la suite

Weber, Ludwig (Internal/Cosupervisor2)  Lire la suite

Blazars are extremely powerful astrophysical objects that emit radiation up to the TeV regime. 1ES 1218 + 30.4 is one such object. It was observed from December 20, 2006, to March 20, 2007, by the γ-ray experiment VERITAS (Very Energetic Radiation Imaging Telescope Array System), an array of four 12-m atmospheric Cerenkov telescopes located in southern Arizona. These observations are analyzed and 1ES 1218 + 30.4 is detected with high significance. The observed spectrum is also found to be in agreement with previous results and is here measured to be (2.2 ± 0.3stat. ± 0.4sys.)×10−12cm−2 s−1 TeV−1(E/0.8TeV)−2.8±0.2stat.±0.2sys. in the 350 …  Lire la suite

Amyotrophic lateral sclerosis (ALS) is a devastating motor neuron disease which results from the degeneration of upper and lower motor neurons in the brainstem, spinal cord and motor cortex. Tragically there is no treatment to prevent ALS. The drug Riluzole acts to delay progression, but only by a month or so in this disease that has a survival length of three to five years. The identification of genes that are mutated in patients with ALS would help devise novel therapeutic strategies as much remains to be discovered about the genetics of ALS. Familial forms of the disease account for only …  Lire la suite

Meunier, Jean-Luc (Internal/Supervisor)  Lire la suite

Le virus de l’hépatite C (VHC) est un virus d’ARN de polarité positive qui appartient à la famille Flaviviridae. Le VHC exprime la protéine non-structurelle NS5B, une ARN polymérase dépendante de l’ARN indispensable à la réplication du génome virale. Nous décrivons ici les propriétés allostériques du site GTP-spécifique (site-G) du VHC polymérase, ainsi que les propriétés allostériques de VIR-1327, un inhibiteur non-nucléoside (INN) qui est dérivé du benzimidazole. En utilisant des tests biochimiques, nous avons identifié certains résidus du site-G qui influencent l’activité du NS5B, incluant sérine-29, proline-495 et valine-499. Nous avons également démontré que VIR-1327 est un puissant inhibiteur …  Lire la suite

Cette thèse est une synthèse de certains problèmes algorithmiques dans la thèoriedes groupes et leur complexité computationnelle. Plus particulièrement, elle présenteune revue détaillée de la décidabilité et de la complexité des problèmes du mot et dela conjugaison dans plusieurs classes de groupes solubles, suivie de deux nouveauxrésultats. Le premier résultat énonce que le problème de la conjugaison dans lesproduits couronne qui satisfont certaines conditions élémentaires est décidable entemps polynomial. Elle part d'une publication de Jane Matthews (1969). Le deuxièmerésultat, basé sur des idées de Remeslennikov et Sokolov (1970) et de Myasnikov, Roman'kov,Ushakov et Vershik (2008), présente un algorithme en temps …  Lire la suite

Paul Stapley (Internal/Cosupervisor2)  Lire la suite

ABSTRACT Guidelines that address the seismic design of cold-formed steel structures are not provided in the 2005 NBCC or in the CSA S136 Specification. The revised version of AISI S213 does, however, contain Canadian provisions for the seismic design of strap braced walls. This standard specifies seismic force modification factors and height limits for the two categories of diagonal strap braced (concentric) walls: Limited ductility (LD) Rd = 2.0, Ro = 1.3, building height limit of 20 m, and Conventional construction (CC) Rd = 1.25, Ro = 1.3, building height limit of 15 m for low seismic zones. In order …  Lire la suite

Les solutions analytiques basées sur des lignes de transmission ont simplifié l'ingénierie de circuits micro-ondes complexes, tel que les EBG. La présente thèse étudie les structures coplanaires EBG à partir d'éléments discrets et de modèles de lignes de transmission, auxquels sont ensuite appliquées des formules analytiques. Grâce à cette approche, un logiciel a été développé permettant de prédire les caractéristiques de dispersion de ces structures périodiques en quelques secondes seulement. Les structures coplanaires EBG contenant des sections courbes sont étudiées et un modèle de circuit équivalent à la portion courbe est proposé. L'analyse des structures EBG commence par une simple …  Lire la suite

Al-Saji, Alia (Supervisor1)  Lire la suite

The neuromuscular junction is widely used as a model to study the formation and function of synapses of the central nervous system. In addition, studies at the neuromuscular junction have provided insight on the molecular mechanisms that govern changes in synaptic structure and strength in response to activity. The precise apposition of the postsynaptic specialization with the complex branched nerve terminal is an essential functional characteristic of synapses. Recently, it was demonstrated that laminin, a key structural protein at the basement membrane, acts as a signaling molecule that can initiate the formation of acetylcholine receptor aggregates on muscle fibers in …  Lire la suite

This thesis considers a joint channel estimation and data detection algorithm for Multiple Space-Time Trellis Codes (MSTTCs) over high Doppler fading channels. This algorithm belongs to the Per-Survivor Processing (PSP) family, where a survivor associated with a trellis state is used for channel estimation. We propose a smoothed data detection technique to increase the probability of the survivor being a correct data sequence. A symbol by symbol Maximum A Posteriori Probability (MAP) criterion, with a fixed delay $D$, is employed for data detection, combined with a Kalman Predictor (KP) for channel estimation. This novel algorithm, called Smoothed Data Detection and …  Lire la suite

The gastro-intestinal (GI) tract represents the largest surface of the body and is continuously exposed to the microbial environment. In such anatomy, the survival of the host requires that the intestinal microbial flora be contained without excessive immune-reactivity to commensal bacteria while retaining the ability to respond to episodic pathogens. The discriminative recognition between beneficial commensal bacteria and potentially harmful pathogens demands an accurate interpretation by the GI mucosal immune system. Any defects in the processes of innate immune recognition and killing may lead to the development and perpetuation of chronic intestinal inflammation, namely inflammatory bowel disease (i.e. Crohn's disease …  Lire la suite

Mucci, Alfonso (Internal/Supervisor)  Lire la suite

Dystroglycan and the integrins are two types of extracellular matrix receptors involved in astrocyte adhesion and migration. The molecular mechanisms that control their distribution to signaling platforms of the plasma membrane remain poorly understood. In the present study, we define four cell spreading stages for adherent astrocytes, termed stage 1 to 4, and defined by the state of spreading of the cell in culture. Immunocytochemistry analysis reveals that DG and integrins distribute differentially depending on the stage, and both receptors get recruited to leading edge of the cell, possibly to GM1-rich lipid rafts, in scratch-induced migration. Treatment of reactive astrocytes …  Lire la suite

Yue, Stephen (Internal/Supervisor)  Lire la suite

This dissertation looks at three different aspects of labour mobility. The first essay examines the movements of workers between wage-employment and self-employment in the United States and the returns to various forms of experience in that context. The second essay studies the long-term unemployed in Canada, and the transitions that they make into other labour market states. The final essay deals with the implications of movements of workers between countries -- specifically, it analyzes earnings distributions to obtain a more complete picture about the declining economic fortunes of immigrants to Canada in recent times. They key contribution of the first …  Lire la suite

Self-esteem is an important construct in psychiatric disorders. We hypothesize that in patients with first onset of a psychotic disorder, self-esteem will be associated with outcome and it will, in turn, be influenced by early life experiences. Methods: The Self-Esteem Rating Scale, The Parental Bonding Instrument (PBI), the Measure of Parental Style (MOPS) and The Childhood Trauma Questionnaire (CTQ) were administered to individuals with first-episode psychosis. Symptoms and the GAF were assessed at entry to the program and at six months. Results: Self-esteem was positively correlated with the GAF, but not with remission status at six months. Self-esteem was negatively …  Lire la suite

In mammals, mitochondria and mitochondrial DNA (mtDNA) are transmitted through the female germline. Mature oocytes contain nearly 200,000 copies of mtDNA, organized at 1-2 copies per organelle. Despite the high genome copy number, mtDNA sequence variants are observed to segregate rapidly between generations, and this has led to the concept of a genetic bottleneck for the transmission of mtDNA. In this thesis, I demonstrate that a subgroup of replicating genomes in the early post-natal ovary is responsible for the rapid segregation of mtDNA. I show that the rate of segregation of mtDNA can be accelerated when mtDNA copy number is …  Lire la suite

Les entomopathogénes vivants juvéniles et adultes comparément aux Steinernema carpocapsae DD136 (P. Nématodes) tués par congélation, ne contenaient pas d'hemocytes adhérent provenant de larves d'insectes lépidoptères de Galleria mellonella ou de Malacosoma disstria in vitro ou in vivo. L'accumulation des hemocytes sur les nématodes morts était associée à la stimulation de la cuticule de la phenoloxidase. Les nématodes vivants et leurs exsudats n'avaient point stimulé l'enzyme. L'exsudat de nématodes vivants avait inhibé des cellules granuleuses et quelques plasmocytes adhérents aux larme, cependant l'exsudat de nématodes morts n'avait pas inhibé ces substances. L'exsudat de nématodes vivants avait aussi provoqué une quantité …  Lire la suite

This qualitative study explores the relationship between Chinese students' practice of adopting and/or using an English name and their identities. I am concerned with why Chinese students agreed or refused to adopt an English name at the inception, how their attitudes towards their English name(s) have changed over time, what criteria they used when choosing their English names, and what the relationship is between their English name(s) and their identities. I understand participants' practice of adopting an English name as the result of the habits of adopting ming and zi in the Chinese naming culture. Participants' English name practice is …  Lire la suite

We simulate directional solidification using a phase field model solved with an adaptive finite element method. For small surface tension anisotropy directed at 45 degree relative to the pulling direction, we have observed three types of morphology: Dendritic, seaweed, and cellular. The seaweed pattern is characterized by alternating tip splitting and the branches have no orientation preference. A crossover from the seaweed to dendritic morphology was noticed when lowering the thermal gradient, consistent with previous experimental findings. We also investigate the influence of anisotropy on the morphology. We find that the thermal gradient, pulling velocity, and anisotropy can determine the …  Lire la suite

Clinical investigations of the effects of dehydration on vocal fold tissue rheology have suggested that vocal fold hydration level has a significant influence on vocal fold vibration, voice quality and vocal health in general. Most previous investigations of the influence of hydration on mechanical properties have been qualitative. Few have used a quantative approach to analyze and estimate water transport from the human larynx. A numerical study of airflow and water transport was thus conducted. The numerical methods were verified by performing experiments and numerical simulations of water transport in a rectangular channel. Two-dimensional and three-dimensional computer models of the …  Lire la suite

This thesis presents estimates of gas hydrate distribution and saturation utilizing data from the four IODP Expedition 311 drilling sites, located at the northern Cascadia Margin. The objectives are to constrain geologic models of hydrate formation by determining mechanisms controlling magnitude and distribution of hydrate occurrences, finding pathways enabling fluid migration, and examining the effect of hydrate on physical properties of the sediment. Well log and core data are used to calculate hydrate concentrations, complemented by pore-fluid geochemical data. Correlation of seismic and logging data is achieved through synthetic seismograms. Lithology and faulting appears to control hydrate occurrences, which contradicts …  Lire la suite

Apoptosis is an evolutionarily conserved form of programmed cell death that is essential for normal development, the maintenance of tissue homeostasis and the elimination of virus-infected and damaged cells. Mcl-1, a Bcl-2 family member, plays a critical pro-survival role in the development and maintenance of both normal and malignant tissues. Mcl-1 expression can be rapidly induced in response to survival factors through induction of Mcl-1 transcription. However, its levels are also tightly controlled by ubiquitin-dependent protein degradation by the 26S proteasome. This rapid protein turnover plays an essential role in the initiation of apoptosis following conditions of stress induced protein …  Lire la suite

On reconnaît souvent que la recherche médicale est une poursuite non seulement estimable, mais aussi obligatoire. Cependant, comme certains critiques ont noté, les assises morales d'une telle obligation demeurent nébuleuses. Les travaux de Daniel Callahan, qui est parmi les plus importants de ces critiques, demeurent peu exploités. Les arguments qu'il formule autour de son concept de l'impératif de la recherche exigent une analyse attentive afin d'entamer un débat interdisciplinaire rigoureux. Un entendement des dimensions idéologiques de l'impératif de la recherche est au cœur de cœur de ce projet. Je propose une analyse conceptuelle de l'idéologie avant d'entreprendre un examen minutieux …  Lire la suite

Many instrumental expositions of collective violence have examined the role of self–interested ethnic/religious entrepreneurs in inciting riots. The concept of scapegoating is frequently used to explain how opportunistic elites attempt to deflect blame onto vulnerable ethnic minorities, particularly during times of socioeconomic and political upheaval. However, the notion of scapegoating is under-theorized in the conflict literature and the question of why elite scapegoating only sometimes leads to violence is seldom addressed. This dissertation seeks to redress the balance by interrogating spatial variations in violence against the ethnic Chinese in Indonesia (a widely scapegoated group) in the late New Order period …  Lire la suite

Physical inactivity is associated with many of the health conditions associated with aging. Even small increases in physical activity can lead to significant improvements in the health of seniors, yet the elderly are the least active of any age group. It has been suggested that physician counseling to increase the prevalence of physical activity in this population might be a useful strategy. However, studies investigating the effect of physician counseling on physical activity participation in seniors have reported inconsistent results. This research was conceived to examine why existing physician-based physical activity promotion strategies for seniors have yielded small, if any, …  Lire la suite

Pour maintenir son avantage innovateur et concurrentiel, le secteur de sylviculture est concentré sur la recherché dans des manières plus efficaces de produire des produits et des marchés courants pour des sous-produits et des technologies. C'est l'extérieure des fibres de pâte qui est d'importance fondamentale pour l'industrie de pâte et papier. Une meilleure compréhension de la chimie et de la morphologie des fibres de pâte Kraft est le raisonnement primaire pour cette thèse de maîtrise. Dons çe recherche nous démontrons que des applications simple et directes de nouvelles technologies (spectroscopie de photoélectron de rayon X, microscopie atomique de force, microscopie …  Lire la suite

Biochemical réglementaire des réseaux sont impliqués dans de nombreux processusessentiels de la vie, tels que les conditions en restant homéostatique, le cycle dedivision cellulaire, et de répondre 'a l'environnement stimuli. Ces réseaux contiennentun grand degré de complexité, qui nous empéche de comprendre comment ils fonctionnent.Deux défis majeurs dans la biologie quantitative sont abordées dans cetteth'ese. Tout d'abord, le probl'eme de l'identification des mod'eles de réglementation 'apartir de données d'observation. Deuxi'emement, révélant les processus par lesquelsles réseaux de régulation évoluent. L'utilisation d'une simple réglementation mod'elequi est basé sur les équations différentielles linéaires par morceaux; les enquêtes surces questions sont mises en …  Lire la suite

Cette thèse comprenait deux études : la biodiversité de cryosols arctiques humides et l'examen de deux biopuces à ADN phylogénétiques en utilisant des échantillons environnementaux du grand arctique canadien. La première partie impliquait des analyses dépendantes et indépendantes des conditions de culture pour évaluer la diversité et la structure des communautés microbiennes. Les communautés des couches actives étaient clairement distinctes des communautés du pergélisol dans les profils DGGE, les librairies de clones 16S pour Bactéries et Archaea de même que les énumérations du nombre total de cellules et du nombre de cellules viables. Les résultats ont indiqué de nouveaux aspects …  Lire la suite

Visual-spatial cognition was examined in typically developing children. Fifty-six children between 3- to 10-years-old completed a comprehensive battery of cognitive tasks that tapped 8 components of visual-spatial functioning. Results demonstrate that task complexity and age interact across the majority of visual-spatial sub-domains, with visual-spatial competencies increasing linearly with age. Examination of acquisition rates showed that after 8 years of age children are capable of performing each measure significantly better than chance. Gender-age-related findings suggest males demonstrate superior visual-spatial mental rotation skills only until 9-10 years of age, than females begin to surpass males. Visual-spatial cognition and mathematical performance was also …  Lire la suite

We interpret theoretically electron pair data observed in Pb(158 AGeV)-Au collisions at the CERN SPS by considering the system as an evolving fireball with parameters fit to experimental observables. Dilepton production in the QGP phase is found via standard finite temperature field theory techniques where annihilating quarks have thermally generated effective masses. After the phase transition, contributions from rho and omega meson decays are found via from experimentally determined forward scattering amplitudes which account for the effects of emission from a medium with finite temperature and density. All results are folded with a model which considers bias created by the …  Lire la suite

Pattey, Elizabeth (Internal/Cosupervisor2)  Lire la suite

Durant l'évolution de la photosynthèse, il est pensé que les diatomées ont acquis cytochrome (cyt) c6, une protéine contenant un atome de Fe, pour le transfert des électrons entre le complexe cyt b6f et le photosystème (PS) I de l'appareil photosynthetique, comme d'autres phytoplanctons ayant les chlorophyll a/c. Ici, nous rapportons l'isolement et clonage du gène de plastocyanin du diatomée Thalassiosira oceanica (CCMP 1005). Le gene codait une protéine contenant un atome de Cu qui est connue de remplacer fonctionellement cyt c6 (contenant un atome de Fe). La sequence inférée de la proteine montrait la plus grande identité avec Emiliania …  Lire la suite

The space elevator has been proposed as an alternate method for launching cargo into space. However, the construction of such a structure requires a material much stronger than any currently in existence. Instead, a partial elevator is considered for satellite placement. In the first part of the thesis, the fundamentals of very long tethered systems are studied. From static analysis on a simple two-body system, it is demonstrated that an assumption made in the conventional analysis does not apply to very long tethered systems. For a uniform tether, the axial stress distribution is obtained. Following the Lagrangian approach, the equations …  Lire la suite

L'hiver pose un défi énergétique pour les endothermes dans les climats tempérés et nordiques. La nourriture est souvent moins disponible et les couts de thermorégulation sont plus élevés. Les animaux peuvent utiliser des adaptations physiologiques et du comportement pour diminuer leur demande énergétique. J'ai exploré l'effet de niveau de nourriture et de la tempérture de l'air (Ta) sur les profils de température corporelle (Tb; 1er chapitre), ainsi que les profils d'activité et les taux métaboliques sur le terrain (FMR; 2e chapitre) d'une population nordique d'écureuil roux (Tamiascirus hudsonicus) en hivers. Les écureuils qui avaient accès a la nourriture supplémentaire maintenaient …  Lire la suite

Cette thèse décrit le développement d'itinéraires synthétiques pour former des carboxylates d'imidazoline, catalysés par le palladium. Le chapitre 2 décrit la conception d'un catalyseur actif pour la synthèse de carboxylates d'imidazoline à partir de deux imines, de chlorures acides et d'oxyde de carbone. En modifiant les conditions réactionnelles, deux imines différentes peuvent être sélectivement incorporées au noyau d'imidazoline. Cette méthode permet d'assembler des imidazolines en un seul pot, avec la possibilité de varier les différents substituants. Cette approche a été employée pour la synthèse d'une large gamme une gamme de carboxylates d'imidazoline. En chapitre 3, une nouvelle synthèse catalysée par …  Lire la suite

Le site Maynard-McKeown regroupe les vestiges d'un village d'Iroquoïens du Saint-Laurent. Trouvé près de la ville actuelle de Prescott, en Ontario, ce site date du XVIe siècle. Pendant l'été 1987, environ le quart de ses 1.6 hectare a été fouillé. On y a fouillé des parties ou l'ensemble de 23 maisons longues, plusieurs palissades, une tranchée, deux huttes à sudation et de nombreux autres vestiges ayant une portée sociale. Aucun autre site Iroquoïen du Saint-Laurent n'a donné lieu à des fouilles aussi extensives que celui de Maynard-McKeown ; c'est aussi le seul à fournir des preuves d'échanges commerciaux avec des …  Lire la suite

The main theme of this thesis is wireless communications using multiple antennas. The thesis consists of four topics on smart antenna technology, its applications to direct sequence code division multiple access (DS/CDMA) communications, and multiple-input multiple-output wireless communications. The first problem under consideration is the joint estimation of direction-of-arrival (DoA), propagation delay, and complex channel gain for antenna-array DS/CDMA communications over frequency selective multipath channels. We propose a subspace based MUSIC-type estimation algorithm which utilizes the spatial smoothing preprocessing technique. The proposed algorithm essentially breaks the multipath induced coherency within the received signals and recovers the full signal subspace spanned …  Lire la suite

RÉSUMÉ L'utilisation de champs électriques pulsés (CEP) dans la transformation d'aliments est une technique de pointe qui nécessite des études approfondies. Une meilleure compréhension de l'effet de traitements CEP sur les modifications structurales, l'hydrophobicité en surface et les propriétés rhéologiques de protéines alimentaires est nécessaire à l'application de cette méthode pour l'amélioration des propriétés fonctionnelles de protéines alimentaires dans les systèmes alimentaires. Deux principaux paramètres CEP furent étudiés: l'intensité du champ électrique, variant de 12 à 25 kV cm-1, et le nombre de pulsions, variant de 10 to 120. L'effet de traitements CEP sur les modifications structurales, l'hydrophobicité en surface …  Lire la suite

Decision making formulated as finding a strategy that maximizes a utility function depends critically on knowing the problem parameters precisely. The obtained strategy can be highly sub-optimal and/or infeasible when parameters are subject to uncertainty, a typical situation in practice. Robust optimization, and more generally robust decision making, addresses this issue by treating uncertain parameters as an arbitrary element of a pre-defined set and solving solutions based on a worst-case analysis. In this thesis we contribute to two closely related fields of robust decision making. First, we address two limitations of robust decision making. Namely, a lack of theoretical justification …  Lire la suite

McEwen, Malcolm (Internal/Supervisor)  Lire la suite

The Canadian supply managed dairy sector is likely to face more competitive pressure from challenges through the World Trade Organization (WTO) and the changing global trade environment. Therefore, it is highly prudent for Canadian dairy producers to focus their concern on their level of competitiveness and how to improve it. This study investigated the competitiveness of Ontario dairy sector based on a sample of farm level data with a Box-Cox transformed econometric cost model. The data were gathered by the Ontario Dairy Farm Accounting Project, for the years 2005, 2006, and 2007. The impacts of output, yield per cow and …  Lire la suite

The success of innate host defence to viral infection depends on the ability of innate immunecells to detect the invading pathogen culminating in the production of cytokines and chemokinesthat disrupt viral replication and shape the platform for innate and adaptive immune responses.Rapid induction of type I IFN is a central event in establishment of the antiviral response, whichis tightly regulated by extracellular and intracellular signals that activate transcription factors(NF-KB, AP-l and IRF). The synergistic action of these transactivators on the promoters of type IIFN genes triggers the immediate early IFN response. which is further amplified by JAK-ST ATsignaling proteins. In …  Lire la suite